This invention relates to load suspensions, and more particularly to four-point suspensions for supporting a load on a supporting surface.
The invention is particularly concerned with suspension systems for supporting loads at four points on a supporting surface. The load may be any one of a wide variety of loads such as are commonly supported (as by legs or on wheels or casters) at four points on a supporting surface such as a floor, or on the ground, or a roadbed. Thus, the suspension system of this invention is applicable to such loads as household appliances (e.g., washers, dryers, refrigerators), industrial equipment (e.g., machinery, cutting tables, etc.), office equipment, (e.g., copying machines), which bear at four points on the floor, and four-wheeled vehicles which bear at four points on various supporting surfaces. The problem with four-point suspensions is that if the supporting surface for the load is uneven, and one of the four points of the supporting surface where the suspension is to engage the supporting surface is not coplanar with the other three, the load will be unstable, having a tendency to rock about an axis extending generally through the highest point of the four and the diagonally opposite point, the load being supported only at three of the four points. This may be readily envisioned by considering the instability of a four-legged chair when a block is placed under one of the four legs. It will be observed that the chair is then unstable, tending to rock on an axis through the point of engagement of the blocked leg with the block and the point of engagement of the diagonally opposite leg with the floor.